The present invention relates to an ultrasonic rotary horn. More particularly, the present invention relates to an improvement in an ultrasonic rotary horn having unique characteristics when operated at a frequency in the range of from about 18 to about 60 kHz, which improvement defines the configuration of the ends of the horn.
The ultrasonic rotary horn described in above-referenced application Ser. No. 07/525,523 is intended to be excited at a frequency of from about 18 to about 60 kHz. The horn comprises a shaped, solid metal object having a radial surface terminated by a first end and a second end, and a rotational axis, in which each of the ends is defined by a surface and the object is axially symmetrical. The horn has the following characteristics:
(A) the diameter of the horn is in the range of from about 4 cm to about 19 cm; PA1 (B) the width of the horn at the radial surface is from about 0.6 cm to about 13 cm; PA1 (C) the thickness of the horn at the rotational axis thereof is from about 0.6 cm to about 15 cm and is independent of the width of the horn at the radial surface; PA1 (D) the horn has a mass in the range of from about 0.06 kg to about 30 kg; and PA1 (E) the diameter, width, and thickness are selected for a desired frequency so that the horn, upon being excited by ultrasonic energy at such frequency which is input at the rotational axis at, and substantially perpendicular to, one or both ends, is adapted to resonate in a manner such that: PA1 (A) the diameter of said horn is in the range of from about 4 cm to about 19 cm; PA1 (B) the width of said horn at said radial surface is from about 0.6 cm to about 13 cm; PA1 (C) the thickness of said horn at the rotational axis thereof is from about 0.6 cm to about 15 cm and is independent of the width of said horn at said radial surface; PA1 (D) said horn has a mass in the range of from about 0.06 kg to about 30 kg; and PA1 (E) said diameter, width, and thickness are selected for a desired frequency so that said horn, upon being excited by ultrasonic energy at such frequency which is input at the rotational axis at, and substantially perpendicular to, one or both ends, is adapted to resonate in a manner such that: PA1 (a) the diameter of said flat portion is at least about 20 percent of the diameter of the horn; PA1 (b) said generally convex portion is a curved surface having axial symmetry and a curvilinear profile in cross-section through said rotational axis which lies in the triangular area defined by (i) a straight line leading from the outer boundary of said flat portion to the edge of said radial surface; (ii) a straight line which is parallel with the rotational axis and which beings at the outer boundary of said flat portion; and (iii) a straight line which is perpendicular to the rotational axis and which extends from the edge of said radial surface to said straight line parallel with the rotational axis; PA1 (c) said horn has a variance of no more than about 20 percent across said radial surface; and PA1 (d) the ratio of the average radial amplitude to the longitudinal amplitude is at least 1.
(1) the excited end moves substantially in phase with the movement of the source of excitation; PA2 (2) the opposing end, whether or not it is actively excited, moves substantially out of phase with the movement of the excited end; PA2 (3) the radial work-contacting surface also moves substantially out of phase with the movement of the excited end; and PA2 (4) the horn exhibits a single nodal point at its geometric center. PA2 (1) the excited end moves substantially in phase with the movement of the source of excitation; PA2 (2) the opposing end, whether or not it is actively excited, moves substantially out of phase with the movement of the excited end; PA2 (3) said radial work-contacting surface also moves substantially out of phase with the movement of the excited end; and PA2 (4) said horn exhibits a single nodal point at its geometric center;
When the width of the horn was of the order of 5 cm, the amplitude across the radial or work-contacting surface (i.e., the radial amplitude) was remarkably constant. As the width of the horn increased to about 10 cm, however, it was found that the radial amplitude varied significantly across the radial surface. It subsequently was discovered that the degree of variation in the radial amplitude (i.e., the variance of the horn) was significantly influenced by the configuration of the ends of the horn.